Method and apparatus for surface treating an axially symmetric substrate at atmosphere pressure

Abstract

A surface treating apparatus which comprises a hollow cylindrical electrode and a counter electrode provided within the hollow cylindrical electrode, and a power supply for applying a potential between the electrode and the counter electrode to cause an atmospheric pressure plasma in the presence of a selected gas to generate within the cylindrical electrode is described. A method is also described, wherein a material to be treated is placed between the electrodes and a potential is applied therebetween to generate the plasma to effect the surface treatment of the material. The method and apparatus are very effective for surface treatment of axially symmetric substrates in the form of bars, tubes or fibers.

What is claimed is: 
     
       1. In a surface treating method which comprises applying a potential between electrodes spaced apart from each other in the presence of a gas at an atmospheric pressure thereby generating a plasma, and exposing a material to be treated to the thus generated plasma, the improvement comprising providing one of the electrodes in the form of a hollow cylinder and the other electrode in the shape of a bar or a tube, placing the other electrode within the one electrode in a spaced relation along an axial direction of the hollow cylinder so that the atmospheric pressure plasma is generated in the inside of the one electrode in the form of the hollow cylinder, and wherein the material to be treated has an axially symmetric shape and is placed in a zone where the plasma has been generated thereby to treat the surface of the material uniformly. 
     
     
       2. The surface treating method according to claim 1, wherein the potential is applied from an AC power supply and at least one of the electrodes is covered with an electrical insulator at a side which is in face-to-face relation with the other electrode. 
     
     
       3. The surface treating method according to claim 1, wherein the other electrode is placed on an axis of the hollow cylinder. 
     
     
       4. A surface treating apparatus wherein a potential is applied between electrodes spaced apart from each other in the presence of a selected gas at an atmospheric pressure thereby generating a plasma, and a material to be treated is exposed to the thus generated plasma, comprising: an electrode in the form of a hollow cylinder, a counter electrode having a bar or tube shape placed in the inside of the hollow cylinder in a spaced relation with respect to the cylindrical electrode along an axial direction of the hollow cylinder, and a power supply for applying a potential between the cylindrical electrode and the counter electrode to generate an atmospheric pressure plasma, whereby a material to be treated which has an axially symmetric shape and is placed between the cylindrical electrode and the counter electrode is surface treated with the atmospheric pressure plasma uniformly.   
     
     
       5. The surface treating apparatus according to claim 4, wherein the material to be treated covers said counter electrode therewith. 
     
     
       6. The surface treating apparatus according to claim 4, wherein said hollow cylinder has an electrical insulator layer on the inner surface thereof.